In any door, window or similar hinged device, between the frame and leaf there is, in the open position of the latter, a considerably wide angle, permitting for example the introduction of fingers such that if the leaf is accidentally closed a severe injury is produced. Therefore, it is necessary to take into account that the force exerted, for example, over a door handle, is multiplied approximately twenty times at the pivot level, due to the lever arm of the door itself, such that injuries may be considerably.
In an attempt to eliminate this problem, door designs are known which are hinged on thei6r upper and lower faces having an edge and housing in a rounded frame, such that the angle is not formed, solving the aforementioned problem, on not permitting the introduction of fingers or any other part of the body/in said space. However, this solution is expensive since it means the replacement of standard doors by special ones.
The availability of an accordion shaped part is also known, as an extension of the classic stepping of the frame, tending to conceal the aforementioned angle, but this solution, besides negatively influencing the aesthetics of the combination, only partially solves the problem since the risk of accidents continues, now between the hinged leaf and the flat iron itself, although in this case, injuries will be slightly less severe, especially when using an easily yieldable flat iron.
A third solution consists of using hinges that displaces the door leaf with respect to the frame, when there is an object in the closing area.
Along this way it is interesting to mention the French patent FR-2571417 in which the upper semi-hinge, instead of being directly fixed to the conventional base plate, which in turn is used to fix the semi-hinge to the corresponding edge of the door, is fixed by means of a mobile arm in which there is a recessed housing containing a rod interlocked to said base plate, so that under normal conditions, the arm of the semi-hinge itself is maintained embedded in the base plate, being jointly mobilised with the latter and the leaf itself, whilst in the event of an obstacle in the closing area, a swinging of the arm is produced with respect to the base plate provoking a distancing of the leaf with respect to the frame, hence preventing damage or injury to objects between these components, such as fingers.
However, this solution only exerts the effect sought in the upper level of the door, whilst at the lower level, the tendency of the total adaptation between the door and the frame is maintained at all times, making the solution effective in the upper area of the door and practically ineffective in the lower part, which is precisely the area with the greatest risks of accidents, especially with respect to children.
Likewise, this solution has another evident and severe drawback from the standpoint of the user's safety, being the great pressure to which the skin of the trapped limb is submitted on displacement of the edge when said trapping occurs.
Finally, from the design standpoint, this solution has the drawback of difficult calibration due to the fact that the elastic component is also supporting.